JP2009184669A - Drive device for power steering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive device for power steering capable of carrying out assembling work by specifying a neutral position where a steering angle of a tire becomes equal right and left. <P>SOLUTION: A device unit (a) to exercise assist force is furnished with an input shaft 3 and an output shaft 4 relative relation of which is specified, and serration 5, 6 the numbers of teeth of which are different from each other is respectively fixed on these input shaft 3 and output shaft 4. The serration 5 of the input shaft 3 is combined with serration 7 of an input mechanism I linked with a steering wheel 1, and the serration 6 of the output shaft 4 depends on the drive for power steering constituted by combination with serration 8 of an output mechanism O linked with the side of the tire 2. Thereafter, marking is applied on the tooth of either one of the serration of the input shaft and the output shaft and at a position a slipping angle of which is the smallest in the relative relation of the serration of the input shaft and the serration of the output shaft. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drive device for power steering in which a relative relationship between an input shaft and an output shaft is specified, and serrations for linking to an input mechanism or an output mechanism are provided on both the shafts.

  Patent Literature 1 discloses a power steering drive device that specifies a relative relationship between an input shaft and an output shaft and links an input mechanism or an output mechanism to both the shafts. This conventional device (torque generator) uses pins to link the input shaft and the output shaft to the input mechanism or the output mechanism. However, when pins are used, there is a problem that the strength is not sufficient.

  Therefore, as a means for solving the problem of the pin, an apparatus using serrations on the input shaft and the output shaft has already been provided. In this type of driving apparatus, an input shaft and an output shaft are provided in a power mechanism composed of a motor or the like, and the relative relationship between these shafts is specified at the stage of assembling them. Each of the input shaft and the output shaft whose relative relationship is specified in this way is provided with a serration, the serration of the input shaft is assembled to the serration of the input mechanism linked to the handle, and the serration of the output shaft is linked to the tire. Assemble the serration of the output mechanism.

  However, the functions required for the serration on the input shaft side and the serration on the output shaft side are slightly different. For example, on the input shaft side, the number of teeth is generally increased to reduce the shift of the handle that occurs when the handle is attached. By doing so, an effect of narrowing the width of the toe-in adjustment can be expected. On the other hand, on the output shaft side, since the load from the tire is large, rather than the above-described problem of deviation, rather the strength is required. Therefore, the serrations on the output shaft and the output mechanism side reduce the number of teeth to maintain strength.

  In the power steering drive device as described above, the serration of the input shaft is assembled to the serration of the input mechanism, and the serration of the output shaft is assembled to the serration of the output mechanism. Will be identified. In other words, the relative relationship between the input mechanism and the output mechanism is determined via the drive device.

JP 11-99957 A

In the serrations between the input shaft and the output shaft, when the relative relationship in the circumferential direction is specified, the deviation angle between the corresponding teeth between the two serrations according to their rotational angle position The law is recognized in the way of the difference. That is, how the deviation angle is generated differs depending on whether the ratio of the number of teeth of the serration between the input shaft and the output shaft is an integer or a decimal. When the ratio of the number of teeth becomes an integer, the deviation angle between the corresponding teeth between the two serrations is the same for any rotation angle.
Further, when the ratio of the number of teeth is a decimal, the shift angle between the corresponding teeth differs between the two serrations according to the rotation angle position. For example, the teeth at specific rotation angles have a small shift angle, but the teeth at other rotation angles have a large shift angle. For this reason, when the relative position of both serrations is specified, the other serration is processed based on one of the serrations so that the deviation angle between the two serrations becomes a target value. However, if the deviation angle is to be kept within the target value as described above, the method such as rolling is not sufficiently accurate, and the serration is manufactured by cutting. Thus, conventionally, since selension is manufactured by cutting, there was a problem that the mass production effect could not be sufficiently improved.

  In addition, in order to keep the deviation angle within the target value as described above, for example, the relative positions of the serration and the shaft coupled to the serration are adjusted so that the deviation angle of both serrations is within the target value. There is also a way to do it. However, even in this case, there is a problem that the productivity is inferior.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a power steering drive device that can perform assembling work by specifying a neutral position where tire steering angles are equal on the left and right.

  The present invention includes an input unit and an output shaft whose relative relationship is specified in an apparatus unit that exerts an assist force, and each of the input shaft and the output shaft has a numerical value in which the ratio of the number of teeth has a decimal number. The input shaft serration is combined with the serration of the input mechanism linked to the steering wheel, and the output shaft serration is combined with the serration of the output mechanism linked to the tire side. Serration or serration of either or both of the serrations of the output shaft, and the tooth having the smallest deviation angle in the circumferential relation between the serration of the input shaft and the serration of the output shaft or It is characterized in that markings are made at positions corresponding to the teeth.

  The second invention calculates the apparent advance angle of each tooth in both serrations of the input shaft and output shaft, and between the individual teeth of the serration on the input shaft and the individual teeth of the serration on the output shaft. The difference is that the difference in the lead angle is calculated, and serrations in which the difference in the lead angle, that is, ½ of the deviation angle is within the preset allowable limit, are used as a pair. The deviation angle refers to the relative difference in the advance angle between the individual teeth of the serration on the input shaft and the output shaft. The advance angle refers to the other for the specific tooth when the specific tooth is used as a reference. The absolute angle of the teeth.

  According to a third aspect of the present invention, the greatest common divisor between the serration pitch angle on the input shaft and the serration pitch angle on the output shaft is obtained, and a value of ½ of the greatest common divisor is a preset allowable limit deviation angle. It is characterized in that it uses serrations inside.

  The marking in the present invention may be not only engraving and printing, but also, for example, by paint or chalk, and any kind of marking is possible if a specific tooth or a corresponding position is marked. May be. In short, it is only necessary to recognize the tooth with the smallest deviation angle when the device is assembled to the input mechanism and the output mechanism. Of course, the serration in the present invention may be either male or female.

  According to the first to third aspects, between the serrations according to the rotation angle position when the relative relationship in the circumferential direction is specified between the serrations in which the ratio of the number of teeth becomes a numerical value having a decimal number. Since the tooth with the smallest circumferential deviation angle between the corresponding teeth is marked, if the neutral position is determined by using the marked position as a point, the tire breaks with respect to the handle angle. The corners can always be equal and the assembly work for that is very simple.

  Further, according to the second and third aspects of the invention, even if the neutral point on the input mechanism side and the neutral point on the output mechanism side are slightly deviated from each other, it is always kept within the allowable range.

It is the schematic of the vehicle incorporating the apparatus unit of this invention. It is an enlarged view of the serration provided in the output shaft. It is the graph which showed the relationship between the shift | offset | difference angle | corner (theta) 2 of the tooth | gear formed with the tooth number Z2 nearest to each tooth | gear formed with the number of teeth Z1, and the shift | offset | difference angle | corner (theta) 1 from a reference point. It is explanatory drawing for demonstrating that 1/2 of a shift | offset | difference angle is in an allowable limit.

  The illustrated embodiment shows a power steering device, and an input mechanism I linked to a handle 1 and an output mechanism O linked to a tire 2 are linked via a device unit a. The device unit a is provided with a power source control mechanism C that controls a power source such as a motor, and the power source control mechanism C is provided with an input shaft 3 and an output shaft 4.

  The input shaft 3 is provided with a male serration 5 and the output shaft 4 is provided with a male serration 6. The male serration 5 provided on the input shaft 3 is more than the male serration 6 provided on the output shaft 4. The number of teeth is increased. However, the reason is exactly the same as in the conventional case. And the input shaft 3 and the output shaft 4 which were made in this way maintain the relative relationship in the circumferential direction, and are kept free to rotate.

  In this embodiment, the male and female serrations 5 and 6 use a pair satisfying the following condition, and there are the following two methods for deriving the condition. The first method computes the apparent advance angle of each tooth in both male serrations 5 and 6, and the individual teeth of male serration 5 on input shaft 3 and the individual teeth of male serration 6 on output shaft 4. And the male serrations whose ½ of the deviation angle is within a preset allowable limit are selected. The allowable limit of the deviation angle is determined in advance by the allowable limit for the neutral deviation between the input mechanism I and the output mechanism O described above.

  The second method is to determine the condition of the pair of male and female serrations 5 and 6, by obtaining the greatest common divisor from the pitch angle of the male and male serrations 5 and 6, and ½ of the value of the greatest common divisor is calculated in advance. This is a method for selecting male serrations that are within the set allowable limits. The greatest common divisor means the minimum difference between the multiples of the pitch angle of the number of teeth Z1 and the pitch angle of the number of teeth Z2. If within limits, both male serrations 5 and 6 are paired for use with the device.

  Note that the second method cannot be used when one or both of the pitch angles of both serrations becomes a decimal, but the first method can be used regardless of the greatest common divisor. Therefore, when one or both pitch angles of both serrations become a decimal, the first method may be used.

  In addition, the reason why ½ of the deviation angle is within the preset allowable limit as described above is as follows. For example, a case where male serrations having the greatest common divisor are 1 and the relative positions of one tooth are completely matched and their shift angles are set to zero will be described with reference to FIG. . In FIG. 3, the X axis indicates a deviation angle θ1 assuming that both male serrations are relatively rotated from the zero point, and the Y axis is closest to each tooth formed by the number of teeth Z1. The tooth deviation angle θ2 formed with respect to the number of teeth Z2 is shown.

  Then, the teeth whose relative positions are completely matched as described above are separated from each other as the deviation angle θ1 increases (characteristic indicated by a dotted line). On the other hand, the tooth having the greatest common divisor deviation angle θ2 at the point of 1 degree decreases the deviation angle θ2 as the deviation angle θ1 increases, and the deviation angle θ2 reaches the zero point. The two are separated again (characteristic shown by the two-dot chain line). When attention is paid to point A where these dotted lines and two-dot chain lines intersect, it is clear that the deviation angle θ2 is ½ of the greatest common divisor. Thus, both male serrations can be used in pairs if the tolerance is within half of this greatest common divisor.

  The above description will be further described with reference to FIG. In FIG. 4, a line 10 indicates a center line in a state where specific teeth Z1a and teeth Z2a of both serrations are completely coincident and overlapped. Lines 11 and 12 indicate center lines of the tooth Z1b and the tooth Z2b having a shift angle of 1 degree. Now, assuming that Z1 rotates in the direction of arrow 13, Z1a and Z2a are separated from each other, and the tooth Z1a moves to the position indicated by the dashed line 14. At this time, the tooth Z1b and the tooth Z2b having a deviation angle of 1 degree gradually approach each other, but if the position where the tooth Z1a reaches the line 14 is 0.5 degrees, the tooth Z1b and the tooth Z2b Is close to 0.5 degrees. Therefore, the range in which the minimum deviation angle is maintained between the male and female serrations 5 and 6 is 1/2 of the greatest common divisor. If this half value is within the allowable limit, 5 and 6 can be used as a pair.

  The male serration 5 maintaining the above relationship is assembled to the female serration 7 provided in the input mechanism I, and the male serration 6 provided on the output shaft 4 is assembled to the female serration 8 provided on the output mechanism O. In this embodiment, the teeth 9a of the male serration 6 of the output shaft 4 and the teeth 6a to be the neutral point with respect to the output mechanism O are marked 9 as shown in FIG. The teeth to be treated are determined as follows.

  That is, by assembling each of the input shaft 3 and the output shaft 4 to which the male serrations 5 and 6 are fixed to the apparatus unit a, the input shaft 3 and the output shaft 4 are integrally rotated unless a load acts on them. Kept. In other words, in this state, the relative relationship in the circumferential direction between the male serrations 5 and 6 is fixed. In this way, the deviation angle of each tooth in male serrations 5 and 6 in which the relative relationship is fixed is measured, the tooth having the smallest deviation angle is selected, and among those teeth, the male provided on the output shaft 4 is selected. As shown in FIG. 2, marking 9 is applied to one or both of the teeth 6 a of the serration 6 and the male serration teeth 5 a provided on the input shaft 3. However, the marking on the input shaft 3 side is not shown.

  The female serration 7 on the input shaft 3 side is set in advance so that the neutral position of the female serration 7 is determined by the neutral position when the handle 1 is held neutral. The female serration 8 on the output shaft 4 side is also set in advance so that the neutral position of the female serration 8 is specified as the neutral position when the tire 2 is held neutral.

  If the marking 9 is provided as described above, the tooth 6a provided with the marking 9 can be incorporated into the female serration 6 in a state in which the tooth 6a matches the neutral position of the output mechanism O. When the male serration 8 is incorporated into the female serration 8 on the basis of the teeth 6a having the marking 9 as described above, the male serration 5 is shifted from the neutral position within the range of the shift angle. When the male serration 5 is incorporated in the female serration 7 in a state where the male serration 5 is shifted from the neutral position in this way, the neutral position of the handle 1 is shifted within the range of the shift angle. However, since the deviation angle is within the allowable range as described above, there is no significant influence.

  Therefore, according to this embodiment, even if the site where the device unit a is assembled and the site where the input mechanism I and the output mechanism O are assembled to the device unit a are different from each other, that is, the device unit a, The relative relationship between the input mechanism I and the output mechanism O with respect to the neutral position can be specified within an allowable limit.

  In the above embodiment, the male serrations 5 and 6 are provided on the input shaft 3 and the output shaft 4 and the female serrations 7 and 8 are provided on the input mechanism I and the output mechanism O side. However, these may be reversed. Of course. That is, female serrations may be provided on the input shaft 3 and the output shaft 4, and male serrations may be provided on the input mechanism I and the output mechanism O side. On the device unit a side, either the input shaft 3 or the output shaft 4 may be male serration and the other may be female serration. In any case, the marking 9 is applied to the serration on the apparatus unit a side. When the subject to which the marking 9 is applied is female serration, the marking 9 may be applied to the tooth itself or a portion corresponding thereto.

a Device unit 1 Handle I Input mechanism 2 Tire O Output mechanism 3 Input shaft 4 Output shaft 5 Serration on the input shaft side 6 Serration on the output shaft side 7 Serration on the input mechanism side 8 Serration 9 on the output mechanism side Marking

Claims (3)

The device unit that exerts the assist force includes an input shaft and an output shaft whose relative relationship is specified, and each of the input shaft and the output shaft has a serration in which the ratio of the number of teeth is a numerical value having a decimal number. The input shaft serration is combined with the serration of the input mechanism linked to the steering wheel, and the output shaft serration is combined with the serration of the output mechanism linked to the tire side. Serration of either one or both of the serrations of the shaft, and in the relative relationship between the serration of the input shaft and the serration of the output shaft in the circumferential direction, the tooth having the smallest deviation angle or its tooth Power steering drive unit with markings at corresponding positions . The apparent advance angle of each tooth in both the input shaft and output shaft serrations is calculated, and the difference in advance angle between the individual teeth of the serration on the input shaft and the individual teeth of the serration on the output shaft is calculated. 2. The power steering drive device according to claim 1, wherein serrations having a half of the index angle and the deviation angle within a preset allowable limit are used as a pair. Find the greatest common divisor of the serration pitch angle on the input shaft and the serration pitch angle on the output shaft, and set the serration that is half of the greatest common divisor within the allowable deviation angle set in advance. The power steering device according to claim 1 or 2, which is used as described above.

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